Thread: Maf voltage issue

I'm having a strange issue with the signal voltage wire. When I turn the key on, it reads .5-.6 volts. When I try to start it it goes dead, 0 volts. If I disconnect the battery, wait a few seconds then reconnect it, it will read the.5-.6 volts until I turn it over. It is a z32 maf in a 95 ser. I know it is connected properly, and has good ground connections.

I just recently swapped the engine, and this is holding me back.


I had it in the car last year and it ran well. I'm pretty baffled, and if anyone has any insight please help. Thanks.

Ken

How can you get voltage with no battery connected, or turn it over?

sounds like 2 wires are crossed some where or possible shorted out.

Edited, thanks. Any insight to the problem?

I'm going to break out the fsm and trace all the wires down. Once I figure it out I'll let everyone know what it was. Thanks.

aah, yeah that makes more sense. I wasnt sure if maybe you had a weird current draw from something else, or if you were just resetting the ecu.

I agree with Mr.sentra. Definitely sounds like something is or was wrong with the wiring. MAFs are very very easy to fry. Do you happen to have a spare MAF of some kind you know is good that you could try swapping in?

I'm kinda leaning toward a ground issue, seeing as I just painted the engine bay.
I have done the blow test and checked the maf seems to be functioning properly with the key in the on position. I know the wiring isn't and hasn't been backwards ever. I have checked a million times.

Ah, much easier to test / resolve. Try grounding it directly to the top of the intake manifold on one of those 10mm bolts. That should give you a much better reference ground than anywhere else.

Even better than the negative terminal on the battery?

one thing to remember (at least how i was taught) is the MAF is measured based on the difference between the positive voltage and the ground wire voltage. Therefore, you want the MAF's ground to be as consistent with the ECU's as possible.

For example, the ECU ground might actually be -11.2V, so if you ground the MAF directly to the battery negative (-12v), you could be off by that much (0.8V), possibly more. However, if you ground the MAF to the same spot as the ECU so it too has a -11.2V ground, then it's more accurate.

Those connections on top of the intake manifold help you accomplish that.

If I'm wrong, though, please someone correct me.